In the course of environmental research, different methods are used. One of them may be bioindication. This approach involves studying the state of certain living organisms to obtain information about their environment. To understand the features of conducting such studies, you should consider what a bio indicator is. This will provide the necessary information about a similar research methodology.
General definition
A bio-indicator is a living organism, and possibly a whole species or community that lives in a particular ecological system and can serve as a reflection of its condition. Moreover, the study assesses the number of individuals in the population, their condition and behavior. Based on the information received, one can judge the presence in the natural environment of pollutants, toxins, carcinogens, etc.
Bioindicators are plants or animals whose condition is directly dependent on their environment. The application of such a technique during the study has many advantages. Sometimes it is only on the basis of bioindicators that it is possible to obtain the necessary information about the state of the environment. Saving money and time for conducting complex physical and chemical analyzes is an undoubted advantage.
Bioindicators are plants and animals that summarize important data on pollutants and the rate of change. They allow you to determine the place of accumulation and the route of entry of harmful substances, the degree and severity of the effect of toxins on living creatures, including humans.
In the course of research, the biocenosis of such indicators is evaluated. At the same time, researchers are interested in both representatives of the fauna and flora. During the observations, it is possible to assess the degree of chronic exposure to toxins even in low concentrations. They affect the functions and general condition of the internal organs of animals, symmetrical parts of the body and their relationships.
Typology
Bioindicators - plants and animals that live in water, air, soil. Such organisms can be bacteria or algae, as well as invertebrates, for example, crustaceans, ciliates, mollusks. Can be used during the study data on fish, animals.
Soil bioindicators are most often plants growing in the wild. According to their condition, you can determine the acidity, moisture capacity, density and temperature of the soil. Also, the appearance of certain plants can determine the oxygen content in the soil, the amount of nutrients, as well as salts and heavy metals.
Conifers can provide soil information throughout the year. In this case, not only morphological indicators are applied, but also a number of biochemical changes. This allows you to get reliable information. Morphological characters are sometimes variable.
So, for example, ordinary nettle can demonstrate how much calcium is in the ground. Some plants are gallophils. They love saline soils. If they grow in a given area, actively colonizing territories, then the land is gradually being salted.
To assess the state of water, bio-indicators such as the larvae of certain insects, certain types of algae, and higher crustaceans, luminous bacteria are being studied.
Bio-indicators of air can be mosses and lichens. Their physical qualities vary greatly depending on the growing conditions.
Features of choice
Plants and animal bioindicators are selected for research according to a certain principle. It was formulated by one of the most famous American ecologists, Yu. Odum. He suggests taking into account the following statements when choosing bio-indicators:
- There are stenotopic and eurytopic species of living organisms. The former are able to live only in certain conditions, so the scope of their distribution is limited. Eurytopic species are widespread in nature, have environmental endurance. Therefore, they are less suitable for research than stenotopic species.
- Larger types of bioindicators are investigated more often than small ones. This is explained by the turnover rate in the biocenosis. In small species, it is higher, therefore, at the time of the study, they may not fall into the sample, especially during the analysis with a long periodicity.
- To select a species or their group for the study, experimental and field information about the limiting values of a certain factor will be required. At the same time, possible compensatory reactions of the bioindicator and the tolerance of the species are taken into account.
- the quantitative ratio of different populations, species, or communities is more indicative; therefore, it is used as a reliable indicator. Only one species cannot fully convey the extent of environmental changes. Such changes need to be considered as a whole, than in only one direction.
It is also worth noting that the best bio-indicators are species that provide an instant response, as well as differing in the reliability of the information provided. The error should not exceed 20%. Also, with the help of such bio-indicators, it should be easy to get the necessary information. The species must be constantly present in nature so that the researcher can evaluate its condition at any time.
Varieties
There are various types and types of bio-indicators. All living organisms suitable for such studies can be divided into two groups:
- Registering.
- Accumulating.
In the first case, living organisms respond to changes in the environment by changing the size of the population. They can also change the appearance of the phenotype, somatic disorders or tissue damage. Various deformities may appear, the growth rate varies. Other clearly visible signs may be present.
For example, lichens, needles of trees, are registration bioindicators. They appear necrosis, chlorosis, dryness. Recording bio-indicators do not always allow to determine the causes of the changes. In this case, additional research will be required to determine why the population, final appearance, distribution in nature, etc. have changed. Such changes can be the result of different processes.
Bio-indicator organisms can be of an accumulating type. They concentrate toxins, pollution inside their body, in different tissues, parts of the body or organs. During the study, the degree of environmental pollution is determined after chemical analysis. For example, the accumulating bioindicator can be shells of crustaceans, insect larvae, as well as some mammalian organs (brain, kidneys, spleen, liver, etc.), mosses.
Living organisms respond immediately to the whole complex of harmful substances that enter the environment. Therefore, to establish the exact concentration of a single toxin, this technique does not allow. But at the same time, the advantage of using bioindication allows you to determine how exactly how much pollution affects the population.
Test organisms
The test organism may be a bioindicator of the environment. These are representatives of flora or fauna, which are used in the quality control of environmental conditions in the laboratory. They conduct relevant experiments. It can be, for example, unicellular, protozoa, arthropods. The test organism can also be plants, for example, mosses or flowering plants.
The main feature of such organisms is the ability to obtain crops from genetically homogeneous plants or animals. In this case, the prototype is compared with the control. This allows you to get reliable information about the offending factor. Otherwise, due to normal individual differences between individuals, it will not be possible to obtain a reliable result.
Analysis methods
Bioindicators and their environmental pollution are investigated using comparative analysis with a control instance. In this case, different approaches can be used.
The first method involves comparing the relevant characteristics outside the area of influence. For example, plants grown in the industrial pollution zone are compared with crops that grew outside the area of anthropogenic influence.
The second method involves comparing the sample with the experimental results. One part of the test plants is contacted in laboratory conditions with contaminated air, soil, water, and the second with clean media.
When using the third technique, historical standards are used for comparison. This, for example, will be advisable in the study of the European steppe. Today, this ecosystem has almost lost its original appearance. It is with how the steppe looked in the past that it is compared in the present.
The fourth technique uses control. This is a certain type of dependence, deviation from which is regarded as a violation. For example, for undisturbed species communities, an appropriate schedule is built. If any deviations are observed, this will immediately be noticeable if two curves are compared.
Bioindication methods
Using appropriate environmental monitoring, bioindicators in nature are investigated. It is conducted both at the micro and macro level. Bioindication studies can be biocenotic and species. In the second case, the presence of the organism in the environment, the frequency of its occurrence, is investigated. The physiological, biochemical, anatomical and morphological properties of the bioindicator can also be investigated.
During the biocenotic study, species diversity is taken into account using a system of relevant indicators, as well as community productivity.
According to the influence of various factors on the system, bioindication monitoring can be specific and non-specific. They study the reactions of the species to the appearance of pollution, toxins in their habitat. With non-specific bioindication, the same reaction can be caused by different factors. If the changes occurring are explained by the influence of only one factor, we are talking about a specific indication.
For example, conifers and lichens can provide information about the cleanliness of the air in the region, about the presence of industrial pollution in their habitats. The list of plant species, animals that live in the soil, is specific for different types of soil. If changes occur in these groups, we can talk about contamination of the soil with chemicals or a change in its structure due to human activities.
Today it is believed that the most effective is the use of instrumental research in combination with bio-indicators. Such symbiosis provides the most complete, reliable information about the state of the population, the impact on it of adverse factors.
Soil bioindication
Using in the study of soil pollution bio-indicators, it is possible to obtain reliable results. Plants provide information on soil fertility. A full analysis of the composition of the soil requires a lot of time and effort. The soil is considered fertile if nettle, raspberries, celandine, valerian, etc. grow on it. These plants do not survive on poor soil.
Moderately fertile soil is given by angelica, lunatic, meadow fescue, etc. Peat mosses, lichens, cranberries, and lingonberries grow on low-fertile soil.
In addition to the indicator of fertility, the composition of the soil can be determined by plants. The presence of a large amount of nitrogen is indicated by such plants as wheat grass, raspberries, goose cinquefoil, knotweed, etc. The color of such plants will be bright green. If it is pale, it means that there is little nitrogen in the soil. In plants, branching and the number of leaves are reduced.
A number of other minerals, acidity and other soil characteristics can be determined in the soil using bioindicators.
Bioindication of air
A bio-indicator is a living organism that significantly changes its qualities when abnormalities occur in the environment. They can be used to determine if air is contaminated. Such pollutants as nitric oxide, sulfur dioxide, hydrocarbon, etc. have a huge impact on phytocenosis.
Plant resistance to similar toxins is different. Even a small amount of sulfur dioxide in the air can be easily determined using lichens. Among plants, the increased content of this type of pollutant can be determined by coniferous trees.
Sensitive wheat, fir, corn, spruce, strawberry, etc. are sensitive to the content of fluoride, hydrogen chloride in the air.
Bioindication of water
For water quality control, bioindication is one of the best methods. Unlike chemical and physical monitoring methods, this approach is the most objective. Special equipment is able to track only some types of pollution. Bioindication reveals complete information about the state of the surrounding aquatic environment.
Monitoring allows you to evaluate for which areas of operation a reservoir is suitable. One of the easiest ways to bioindicate water is to use yeast cultures. A nephelometric assessment of the turbidity of the liquid is carried out. It depends on the amount of yeast in the sample. If water impedes their development, the sample will be lighter than the control sample.
Fish can also be used as a bio-indicator. They accumulate toxins in their body. As a result, it is possible to establish what qualities the water in a river or lake is characterized by visually assessing the condition of the fish.